In today's world, unfortunately, existing and even certain proposed wireless communications network systems costing many millions of dollars have failings of one type or another. Consider, for example, existing wireless wide area data networks which support communication between a remote or mobile field unit and a base station. These networks either use terrestrial or satellite-deployed base stations. Terrestrial systems can be further classified as either one-way or two-way. Some terrestrial and satellite systems that cost less allow remote users to receive data but provide poor or no capability for remote users to send data. Although some systems support two-way data transfer, these typically provide only limited geographic coverage, which is related to the coverage radius of their transmission towers. In addition, such networks also typically exhibit relatively poor penetration of building structures, due to the high carrier frequencies at which they operate.
Other existing and proposed two-way terrestrial commercial systems include cellular networks and mobile data networks that, do not, by design, cover the entire continental United States. It is estimated that over 40% of the United States does not have commercial wireless data service. Many remote privately owned assets are in these areas and need to be economically monitored. The data rates of these systems may be quite high, but each system requires the users to be within a close range, generally 10 miles or less, of the system infrastructure. This infrastructure is extremely expensive, requiring hundreds of millions of dollars to build a nationwide network. It can sometimes be cost effective to build such infrastructure in areas of high population density, and indeed, roughly 90% of the United States population can be supported by such systems. It is simply not economical for providers of such services to install the required infrastructure in remote areas of low population density, however. In addition, local infrastructure may be subject to manmade or natural disasters.
Several satellite networks, both existing and proposed, have been designed to address the issue of poor geographic coverage. These satellite-based systems typically require a tremendous investment in infrastructure. The infrastructure is located in orbit where it cannot be installed, maintained or replaced without large expenditures for space-launch vehicles. In addition, the mobile subscriber devices required to communicate with such systems are relatively expensive. Furthermore, the field devices need to be within the line of sight of the satellite, since they must typically have overt, high gain electromagnetic reception devices such as dishes or long antennas. Such systems are thus impractical for certain applications.
An example is the problem faced by the manager of fleet vehicles. The assets for which the manager is responsible are highly mobile, and they can be located virtually anywhere. These assets are easily stolen and expensive to insure, and such assets can also become unproductive when it cannot be located or are out of communication ranges. Similar problems exist in other industries as well. For example, there is increasing pressure on the railroad industry to move towards scheduled service, to facilitate just-in-time delivery in an effort to better compete with the trucking industry. To achieve this goal, the manager of a railroad system would ideally be able to quickly determine the location of each and every rail car on a regular basis, no matter where the rail car is located. Optimum routing and delivery time may then be accurately predicted.
In such applications, it would be advantageous to be able to query a remote device in order to determine its status and location, but with minimum cost. Current cellular mobile service costs are increasing as the carriers move from 2G, 3G to 4G and 5G. In addition, higher data rates over limited capacity communications channels are increasing congestion, and transmissions are lost. Increasingly, basic machine-to-machine and emergency communications cell data services are becoming unreliable and more expensive.
Other industries, such as the trucking and shipping industries, struggle with the lack of the ability to track accurately and inexpensively the location of shipping containers no matter where they are located. Any one shipping container may hold thousands or potentially millions of dollars of valuable goods. Clearly, it would be advantageous to know where they are at all times.
Similar demands are made in remote meter or sensor reading, facility monitoring, security, buoy monitoring, and other applications. Applicants have recognized that while some needs of such application could be met by combining a position sensing device such as a Global Positioning System (GPS) receiver unit together with an existing two-way mobile data communication device such as a cellular or satellite transceiver, the system would nevertheless exhibit the aforementioned difficulties of high installation and operation cost, and be subject to the inability to operate in anything but a region of direct line of sight or close proximity to the system infrastructure.